Pressure-responsive device



June 10, 1952 H. SCHAEVITZ PRESSURE RESPONSIVE DEVICE fry/m [Ye/"mmJcaevz? ww- 02 222 .y W him w 1 L 2 w 7. 5 e m 7 I n a 1i; M2

Patented June 10, 1952 UNITED STATES PATENT OFFICE 2,600,271PRESSURE-RESBONSIVE DEVICE Herman Schaevitz, Collingswood, N. J

Application June 19, 1947, Serial No. 755,561

This invention relates to pressure-responsive devices and moreparticularly to a novel device of this character which is adapted to beoperated by fluid pressure and which is substantially unaffected bytemperature changes.

A common form of fluid pressure-responsive devices is one which employsa bellows member or the like wherein the fluid pressure acts on adiaphragm at one end of said member to move the diaphragm against theresisting action of the bellows. Where differential pressures areinvolved, two opposed bellows may be interconnected and may be subjectedto the different pressures respectively. Prior devices such as thosementioned, are generally subject to the objection that they tend to beactuated undesirably by ambient temperature changes and/or changes oftemperature of the fluid.

One object of the present invention is to provide a device which isresponsive only to pressure variations and is substantially immune totemperature variations. 7 1

Another object of the invention is to provide such a device of simpleconstruction and which may be manufactured easily and economically.

Other objects of the invention will be apparent from the followingdetailed description.

In the accompanying drawing,

Fig. 1 is a longitudinal sectional view of a device constructedaccording to the present invention;

Fig. 2 is a transverse sectional view taken along line 22 of Fig. 1; and

Fig. 3 is a view, partly in elevation and partly in section, showing theapplication of the device for a difierent purpose than that illustratedin Fig. 1.

Referring first to Figs. 1 and 2, in the form of the device illustratedthere is provided a cupshaped member I and an associated inclosuremember 2 threadedly secured to member I as at 3. The two members I and 2form a fluid chamber 4 to which fluid under pressure may be suppliedthrough the tubular extension 5 on member I, said extension havingthreads 6 for attachment to a conduit or other means through which thepressurized fluid may be transmitted from a suitable source. The member2, which constitutes a wall of chamber 4, is centrally apertured toaccommodate the elements now to be described.

A pair of bellows members I and 8 have extended end portions 9 and Illrespectively which extend into the aperture of wall 2 and are supportedby said wall, e. g. by a retaining ring II and by being soldered orotherwise secured to the Wall. The wall 2 is of increased thicknessabout 3 Claims. (Cl. 137-786) the aperture therein to provide arelatively wide circular portion I2 which cooperates with the ring II toretain the end portions of the bellows members. It will be noted thatthe bellows member 1 extends exteriorly of the chamber 4 while thebellows member 8 extends interiorly of said chamber. The bellows member'I has a closed end I3 constituting a diaphragm, while the bellowsmember 8 has a generally similar end portion I4 which however, isapertured to admit the pressurized fluid into the otherwise closedchamber I5 formed by the two bellows members. As shown in Fig. 2, thediaphragm I4 preferably has a plurality of circularly arranged openingsI8 so as to freely admit the pressurized fluid to the chamber I5. Thetwo opposed diaphragms" I3 and I4 are interconnected by a rigid memberI! extending axially of the chamber I 5. The member I! may be in theform of a metal rod which is substantially unafiected by any temperaturechanges that may be expected to occur. It is to be understood however,that the said member may be formed of any suitable material other thanmetal.

It will be seen from the description thus far, that the pressurizedfluid is supplied to the chamber [5 within the bellows members, and suchfluid is also'applied to the exterior of the bellows member 8 within thecompartment 4. Hence it will be seen that the head or diaphragm I3 ofbellows I will be moved by the fluid pressure against the resistingaction of both bellows members. Thus when the fluid pressure increases,the diaphragm I3 is moved toward the left against the tensionalresistance of bellows I and against the compressional resistance ofbellows 8. The interconnected opposed bellows members may be likened totwo springs and these two members effectively provide a double restoringforce for the diaphragm I3. Any change in ambient temperature or in thetemperature of the fluid will have no efiect upon the diaphragm I3 dueto the rigid connection between it and the opposing diaphragm I4.Consequently, the diaphragm I3 will be moved only by pressure variationsof the fluid supplied to the device.

The movement of the diaphragm I3 in response to pressure variations maybe utilized for any desired purpose. In Fig. 1 there is shown anelectrical pick-up which may be utilized to indicate the movements orposition of diaphragm I3 by converting them to corresponding magnitudesof self inductance or mutual inductance. As illustrated, the electricalpick-up comprises a plurality of coils I8 wound on a support I9 which issecured to the wall member 2- by means of suitable fastening elements20. A magnetic core 2| is mounted on the extended end of member I! andis movable within the coils l8 to create a varying magnetic field. Acover 22 serves to enclose the pick-up device and the bellows I, thesaid cover being engaged with the member 2. Wires which would benecessary to supply power to the coils and to carry the signals from thecoils to the electrical indicator or controller are not shown since thenecessity for these connections is understood by those familiar with theart.

Fig. 3 is intended merely to show that the device of this invention isapplicable to a wide variety of uses. As illustrated, the device mayserve to actuate an indicating device comprising a dial 23 and a pointer24. The device of the present invention is represented generally at 25and it serves to actuate a gear sector 26 which meshes with a pinion 21within the indicating device. In this instance, the member I! isextended and is connected to the gear sector 26 by means of a link 28.Thus the device of this invention may serve as part of a pressure gaugewhich also includes the dial indicator shown in Fig. 3.

From the illustration of Fig. 1 it will be seen that the'device providedaccording to the invention is extremely simple in construction, and theparts. thereof may be produced at low cost and may be. easily assembled.Thus the invention provides a simple pressure-responsive device which issubstantially immune to temperature variations and which also hasthedouble restoring action above mentioned.

It is tobe understood, of course, that the inventionzis. not limited tothe specific structure shown and furthermoreit is applicable to any usewhere it is desired to translate pressure variations into mechanicalmovements for any desiredpurpose.

I claim:

1. A pressure-responsive device, comprising a pair of opposed expansibleand contractible members having substantial tensional and compressional,resistance and constructed and arranged ,to form a chamber, one of saidmembers having at least one unrestricted opening therein to admit fluidfreel to said chamber, means for supplyingfluid under pressure to saidopening andvfor applying such fluid to both sides of said one member,said chamber being closed to fluids other than the aforementioned fluid,and a rigid connection between the ends of said members,

whereby the end of the other member is movable by the fluid pressureapplied only to its interior against the resisting action of bothmembers and is substantially unaffected by changes in ambienttemperature or changes in the temperature of said fluid.

2. A pressure-responsive device, comprising a fluid chamber, means forsupplying fluid under pressure to said chamber, said chamber having anopening in a wall thereof, a first resistive bellows member extendingfrom said wall exteriorly of said chamber and being closed at its end, asecond resistive bellows member'extending from said wall interiorly ofsaid chamber and forming with said first bellows member an auxiliarychamber which extends through said opening, said second bellows memberhaving openings in its end through which said auxiliary chamber freelycommunicates with said first chamber, said'chambers being closed tofluids other than the aforementioned fluid, and a rigid connectionbetween the ends of said bellows members whereby the closed end of saidfirst bellows member is movable in response to thepressure of said fluidagainst the resisting action of both of said bellows members and issubstantially unaffected by changes in ambient temperature or changes inthe temperature of said fluid.

3. A pressure-responsive device, comprising a generally cylindricalmember forming a chamber and fixedly supported centrall of its ends andthe oppositely-extending halves of which are longitudinally expansibleand contractible and having substantial tensional and compressionalresistance,- said chamber having at least one unrestricted opening toadmit freely fluid under pressure, means for supplying fluid underpressure to said chamber through said opening and for applying suchfluid to the exterior surfaces of the half of the member containing saidopening, said chamber being closed to fluids other than theaforementioned fluid, and a rigid connection between-the ends of saidmember, where by the end of the closed half of said member is movable bythe fluid pressure applied only to its interior surface and issubstantially unaffected by changes in ambient temperature or changes inthe temperature of said fluid.

HERMAN SCI-IAEVITZ.

REFERENCES CITED The, following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,301,301 Mallory Nov. 10, 19422,400,048 Jones May 7, 1946 2,497,255 Brown Feb. 14, 1950

